Elimination of manganates in the production of tri-alkali phosphates from ferrophosphorus



Patented Dec. 12, 1933 PATENT orricr.

ELIIHINATION OF MANGANATES IN THE PRODUCTION OF TRI-ALKALI PHOS- V PHATES FROM FERROPHOSPHORUS George Klein, Chicago, Ill., assignor to Victor Chemical Works, a corporation of Illinois No Drawing. Application January 11, 1932 Serial No. 586,078

3 Claims. (01. 23-106) This invention relates to'improvements in the preparation of tri-alkali phosphate from ferrophosphorus, and more particularly to the preparation of tri-sodium phosphate.

In carrying out the preparation of tri-alkali phosphate from ferro-phosphorus and an alkali or an alkali carbonate, there is frequently present in the ferro-phosphorus a minor proportion of manganese which, under certain conditions, may cause considerable difliculty. Manganese has a tendency to form an alkali manganate, such as sodium manganate, where a sodium alkali is used, which, being soluble, goes through the leaching process into the crystallizers where it is converted into manganese dioxide and causes a discoloration of the crystallized tri-sodium phosphate.

In accordance with this invention, the formametal carbonate such as sodium or potassium carferro-phosphorus having other phosphorus contents.

The mixture is then heated in an oxidizing atmosphere at a reacting temperature, preferably below fusion, and the tri-sodium phosphate thereafter leached out as by an alkaline leaching liquor and the tri-sodium phosphate crystallized therefrom, for example as set forth in the copending application of Howard Adler, Serial No. 566,182, filed September 30, 1931.

The use of the excess of ferro-phosphorus does not interfere with the efliciency of the operation since it is oxidized to ferric phosphate during the process and when acted upon by alkali in the leaching process, it is converted to tri-sodium 7 phosphate.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be 7 contrued as broadly as permissible, in view of the prior art.

WhatI regard as new, and desire to secure by Letters Patent is:

. 1. The process of producing tri-alkali phos- 30 phates by heat treatment of admixed ferro-phos phorus containing manganese and an alkaline substance of the group consisting of alkali hydrates and alkali carbonates, characterized by preventing the formation of alkali manganate by 35 incorporating an excess of the order of to 5% over the chemically equivalent amount of ferrophosphorus with said alkaline substance.

2. The process as set forth in claim 1, characterized by incorporating an excess of from -5% of 'ferro-phosphorus above the chemically equivalent amount.

3. The method as set forth in claim 1, characterized by incorporating an excess of 1% of ferrophosphorus above the chemically equivalent amount.

GEORGE KLEIN. 

